One point that keeps getting overlooked, especially by the liberals who care so much, is made by Ann here.
"Such people have to be separated from civil society, for the public's sake as well as their own."
Yes, it is better for the mentally ill to actually NOT commit a crime. It is better for them and it is better for us. Hollywood gave us "Minority Report" to refute the notion that we cannot accurately predict someone's future criminal intent, but it is possible to lock up those who cannot function in society until they can.